A cellular phone is an exemplary “mobile unit”, a general name used to describe an electronic device which communicates through one or more wireless links with other devices. A mobile unit can be moved from location to location, be positioned at a certain location, or be in continuous movement. Its location or “position” may be determined at any given moment. The term “positioning” describes the process of determining the location of the mobile unit.
There are two positioning concepts, known as “mobile unit-based” and “network-based”. In “mobile unit-based” positioning, the location of the mobile unit is determined in the mobile unit, using signals received by the mobile unit. GPS (Global Positioning System)-based positioning represents a specific example of mobile unit-based positioning. A GPS receiver in the mobile unit determines its location through measurement of the time of arrival of signals arriving from satellites. Upon activation, the GPS receiver scans for signals from at least four satellites. Due to the low level of the signals arriving from the satellites and the need to receive the signals directly and not through reflections, the GPS receiver needs a clear view of the sky to achieve a successful position fix. Consequently, the GPS operation is very limited inside buildings and other enclosed spaces.
The “network-based” positioning concept is based on measurement, by one or more receivers of a network, of signals emitted by the mobile unit and calculation of its location based on properties of the received signals. The network may be an outdoor (external) network (for positioning a mobile unit outdoors) or an indoor access point (AP) based network (for positioning a mobile unit indoors or “in a building”). Access points are communication devices installed in a building. In indoor AP network-based positioning, the location of the mobile unit is determined through identifying signals received at the APs from the mobile unit. The signals are relayed by each AP to an indoor location server which calculates the mobile unit position. External network-based and GPS-based positioning require good direct communication links with the mobile unit, a condition that usually can not be satisfied inside buildings. There is no known indoor “mobile unit based” positioning concept based on reception of signals from an AP network.
The positioning of mobile units may be used to enable wireless location-based services (LBS) or location-based applications (LBA), which are emerging as a new opportunity for mobile network operators and other entities to generate new revenue. Industry analysts predict very steep growth in LBS and LBA in the near future. Services such as driving directions, identifying closest banks or restaurants, or tracking people for safety or in emergency situations (via E-911 in North America and E-112 in Europe) are already deployed by wireless network operators. These LBSs and LBAs are mainly applied in outdoor environments.
Some LBSs and LBAs are also known in indoor environments. Examples include navigation in large enclosed areas such as airports and shopping malls; providing the location of an emergency caller to rescue forces and first responders; and complementing other outdoor location based services when the mobile unit is inside buildings and can be identified by the outdoor positioning system. There is a clear interest in extending current and future outdoor LBSs and LBAs to indoor environments. However, there is a major problem with such an extension: since outdoor LBSs and LBAs are based on outdoor positioning capabilities (e.g. GPS or network-based) and since the move indoors limits these outdoor positioning capabilities, outdoor LBSs or LBAs become impossible to apply or become useless indoors.
FIG. 1 shows the prior art relevant to outdoor positioning of a mobile unit using GPS. Each mobile unit (e.g. 102 and 102′) is equipped with a main data link (MDL), which is a communication link used by the mobile unit for transferring data to and from a communication network (exemplarily a cellular network) based on wireless technology. While outdoors with clear view of the sky, the GPS receiver in each mobile unit receives the signals of multiple satellites 104, decodes their time of arrival and calculates the distance to each satellite. Since the location of each satellite is known at each moment, the GPS receiver can determine its location based on triangulation in a well-known way. Mobile unit 102 is capable of transmitting a message including its location to a base station (BTS) 106. Base station 106 can deliver the location of mobile unit 102 to an outdoor (also referred to herein as “external” or “remote”) location server 108 through a communication network 110. The outdoor location server is used to process and implement outdoor LBSs and LBAs based on the location of a mobile unit, as mentioned above. The location of the mobile unit has an important role in each such service or application. When the mobile unit (marked as 102′) is located inside a building 112, it cannot receive adequately the signal of the satellites and cannot have its location determined by GPS or by external network positioning.
FIG. 2 shows the prior art relevant to indoor positioning of a mobile unit using an AP network. A mobile unit 202 is located inside building 112. Access points 204 (shown as AP1, AP2, AP3 . . . APi) communicate with the mobile unit and provide information on the signal received from the mobile unit to an indoor location server 202, which determines the location of the mobile unit-based on the information received from one or more APs. In some embodiments, indoor location server 302 may further use the mobile unit location data to activate a LBS or LBA in the indoor environment.
In order to enable the continuation of external (outdoor) LBSs or LBAs inside enclosed spaces (indoor environments) using the same servers, data bases, “look and feel” etc., there is a need for and it would be advantageous to have methods and systems which use indoor positioning instead of outdoor positioning and which provide the indoor mobile unit location data to the server running the location based service or application. There is also a need for and it would be advantageous to have methods and systems that enable the mobile unit to toggle seamlessly between outdoor and indoor positioning, regardless of whether the outdoor positioning is network-based or mobile unit-based.